Air operated door opener

ABSTRACT

A pneumatically powered system for controlling a pneumatic cylinder having a double acting piston connected to a door for moving same between opened and closed positions. Opening of the door is activated by a pressure sensitive mat which directs the flow of pressurized air from a source to the control system which opens the door. A pneumatic timer controls the period of time during which the door remains open, and it produces a signal at the end of the time period which closes the door. The control system includes means for checking the door movement near the fully opened position and near the fully closed position.

United States Patent Hewitt et al.

1 1 Nov. 25, 1975 [54] AIR OPERATED DOOR OPENER 3,026,696 3/1962 Wenzel et al. 91/356 X 4 4 [75] Inventors: Lew V. Hewitt; Dee D. Horton, Jr., 95% 9/196 Hewitt 91/355 X both of Corpus chnstl Primary Examiner-KennethDowney {73] Assignee; Overhead Door Corporation, Dallas, A orney, ge FirmW00dhamS, Blanchard &

Tex. Flynn [22] Filed: Oct. 24, 1973 ABSTRACT [21] Appl- 409,245 A pneumatically powered system for controlling a pneumatic cylinder having a double acting piston con- 52 us. Cl. 49/265; 49/137; 49/138; acted to a door for moving Same between Opened 49/360; 91/3] and closed positions. Opening of the door is activated 51] Int. cl. EOSF 15/02 by a Pressure Sensitive mat which directs the how Of [53] Field f Search 49/265, 266, 29, 30, 137, pressurized air from a source to the control system 49/138, 118, 360, 264; 91/355, 356 which opens the door. A pneumatic timer controls the period of time during which the door remains open, [56] References Cited and it produces a signal at the end of the time period UNITED STATES PATENTS which closes the door. The control system includes I means for checking the door movement near the fully g at 91/355 opened position and near the fully closed position. ay en 2,619,073 11/1952 Brooks et a1 91/355 X 8 Claims, 12 Drawing Figures US. Patent Nov. 25, 1975 Sheet 2 of5 3,921,335

US. Patent Nov. 25, 1975 Sheet3of5 3,921,335

US. Patent Nov. 25, 1975 Sheet40f5 3,921,335

Sheet 5 of 5 US. Patent Nov. 25, 1975 UZA AIR OPERATED DOOR OPENER FIELD OF THE INVENTION This invention relates to a door operator and, more particularly, to a pneumatically powered system for controlling a pneumatic cylinder having a double acting piston connected to a door for opening and closing the door.

BACKGROUND OF THE INVENTION Electrically powered and hydraulically powered door operators have been known for some time and the invention disclosed in this application has been prompted by a desire to improve upon the electrically and hydraulically powered systems. I-Ieretofore, the electrically operated systems and the hydraulically operated systems have held an advantage in the market place over the fully pneumatically operated door control systems due to the smallness in size of the valves which control the application of pressure to the opposite ends of a double acting power cylinder. Thus, a small and compact control valve arrangement suitable for a pneumatical operation has been devised to avoid the problems of the electrical and hydraulic systems, spe cifically, it eliminates shorting around the door opening and the leakage of hydraulic fluid in and around the door opening.

Accordingly, it is an object of this invention to provide a pneumatically operated system for controlling the application of pressurized air to opposite ends of a cylinder having a double acting piston to control the opening and closing movements of a door connected to the piston.

It is a further object of this invention to provide a pneumatically operated door control which does not include electrically operated components and wherein the control of the primary air valves is by pilot valves which are responsive to relatively low volumes of pressurized air, the pressure being sufficient to move the piston longitudinally of the cylinder and thereby move the door between the open and closed positions.

It is a further object of this invention to provide a pneumatic timer responsive to the same air pressure, which is utilized for opening and closing the door, for effecting a delay in the closing of the door.

It is a further object of this invention to provide a single pilot operated air valve for controlling the speed at which the door is moved between the opened and closed positions, said valve connecting said cylinder to the atmosphere when the door is in the closed position so that the door can be opened manually should there be a failure in the supply of pressurized air.

It is a further object of this invention to avoid the use of electrically or hydraulically powered components so as to eliminate the hazards of electricity as well as the hazards from the leakage of hydraulic fluid in and around the door opening.

It is a further object of this invention to provide pneumatic circuitry which may be easily assembled and easily maintained and which provides a system that is essentially silent in operation and practically maintenance free.

SUMMARY OF THE INVENTION The objects and purposes of the invention have been met by providing a pneumatically operated system for controlling a pneumatic cylinder having a double acting piston connected to a door to move same between the opened and closed positions. The door opening movement is initiated by depressing a pressure sensitive mat. A valve means senses the pressure applied to the mat, hence, pressurized air supplied to one end of the cylinder to effect a door opening movement. A pneumatic timing circuit is activated by the appliction of pressure to the mat to control the period of timing during which the door remains open following the removal of the external pressure from the mat. The pneumatic timer thereafter directs the supply of pressurized air to the other end of the cylinder to effect a closing movement of the door. Door position sensing means are provided for checking the movement of the door when it reaches selected positions in its opening and closing movements.

Other objects and purposes of this invention will be apparent to persons acquainted with door control systems of this general type upon reading the following specification and inspecting the accompanying drawings in which:

FIG. 1 is a pneumatic circuit diagram illustrating a system for controlling the movement of pressurized air to the ends of a cylinder having a double acting piston to control the movement of the door;

FIG. 2 is similar to FIG. 1 except that a signal has been applied to the control system and certain ones of the air control valves have been shifted to facilitate a rapid door opening movement;

FIG. 3 is similar to FIG. 1 except that the door is adjacent the fully opened position and circuitry has been activated to slow the door movement down reaching the fully opened position;

FIG. 4 is similar to FIG. 1 except that the signal which initiated the initial door opening movement has been turned off;

FIG. 5 is similar to FIG. 1 except that the penumatic timing circuit has activated a circuit to facilitate a rapid closing movement of the door;

FIG. 6 is a view similar to FIG. 2 except that circuitry has been activated to slow the door down adjacent the fully closed position;

FIG. 7 is a modified pneumatic circuit diagram illustrating a system for controlling the application of pressurized air to the ends of a cylinder having a double acting piston to control the movement of the door;

FIG. 8 is similar to FIG. 7 except that a signal has been applied to the control system and a certain one of the air control valves has been shifted to facilitate a rapid door opening movement;

FIG. 9 is similar to FIG. 7 except that the door is adjacent the fully opened position and circuitry has been activated to slow the door movement down prior to reaching the fully opened position;

FIG. 10 is similar to FIG. 7 except that the signal which initiated the initial door opening movement has been turned off;

FIG. 1 l is similar to FIG. 7 except that the pneumatic timing circuit has activated a circuit to facilitate a rapid closing movement of the door; and

FIG. 12 is a view similar to FIG. 7 except that circuitry has been activated to slow the door down adjacent the fully closed position.

Certain terminology will be used in the following description for convenience in reference only and will not be limiting. The words up, down, right and left will designate directions in the drawing to which prior to reference is made. The words in and out will refer to directions toward and away from, respectively, the geometric center of the various components and designated parts thereof. Such terminology will include the words above specifically mentioned, derivatives thereof and words of similar import.

DETAILED DESCRIPTION For purposes of illustration, FIG. 1 is a schematic diagram of a door control system when the door is in the fully closed position. The solid lines in the circuit are pressurized from a source of pressurized air 11 and the broken lines are not under pressure at the time. This same type of circuit illustration is used in FIGS. 2-6 which illustrate the shifted positions of the various air control valves depending upon the direction of movement of the door as well as the position of the door.

Referring now more specifically to the circuit of FIG. 1, the door control system 10 comprises a source of pressurized air 11 which is supplied through a main distribution line 12 to several subdistribution lines 13, 14, 15, I6 and 17.

The subdistribution line 13 is connected through a two position, air operated, spring return pilot controlled valve 18 to a line 19 which is connected to an air operated pilot valve 21 of a two position, air operated pilot controlled valve 22 as well as a second air operated pilot valve 23 on an air operated pilot controlled valve 24 through a conduit 26. The control valve 24 is returned to the normal position by a return spring 25. The air operated pilot controlled valve 18 is shiftable leftwardly by a signal produced from a fluidic mat 27, which signal is a pressure signal created by a person stepping on the mat whenever it is desired to open the door, which signal is applied to an air pilot valve 28 of the valve 18. A spring 29 schematically illustrated serves to return the valve 18 to the position illustrated in FIG. 1 when the mat signal applied at 27 is turned off such as by the removal of the applied external pressure to the mat. I

The conduit 26 is also connected to another conduit 31 which in turn is connected to an input to a two input, single output OR function valve 32 which has a functional characteristic such that whenever an input is applied to the input connections 33 and/or 34, an output is produced at 36 which is, in turn applied to the air pilot valve 37 of a two position, air operated pilot controlled valve 38.

The subdistribution line 14 is connected through the valve 22 to a conduit 39 which is connected to an input port to a cam controlled, air control valve 41.

The subdistribution line is connected through the control valve 38 through a conduit 42 which is connected to an input to a two position, cam operated air control valve 43. In this particular embodiment, the position shown in FIG. 1 of the valve 43 is such as to block the flow of pressurized air from the pressurized source of air 11.

The air control valves 22 and 38 serve to control the air at opposite ends of an elongated, pneumatic cylinder 44. One end 46 of the cylinder 44 on one side of the double acting piston 47 is connected through a conduit 48 through the valve 38 to a conduit 49 and thence to an input 50 of an air operated pilot controlled valve 51 which is shiftable between two positions by two air pilot valves 52 and 53 as well as by a return spring 54 which shifts the valve rightwardly whenever the air pilot valve 52 and 53 are connected to exhaust such as is illustrated in FIG. 2. The right end 56 of the cylinder 44 is connected through a conduit 57 through the valve 22 to the conduit 49 and thence to the input 50 to the control valve 51. The valve 51v is shiftable between two positions wherein the input 50 to the valve is connected direct to an exhaust outlet 58 and, in the alternative, to a restricted air flow valve, such asa restricted orifice valve 59.

The piston 47 in the cylinder 44 is connected through an elongated piston rod 61 which extends through one end thereof to a bracket assembly 62 which is fastened to a movable door assembly 63 mounted on a track 64. An elongated cam 66 is secured to the bracket assembly 62 and extends generally parallel and coextensive with the elongated cylinder 44 when the door is in the closed position. It is to be recognized, however, that this arrangement is specifically utilized in order to minimize the space of the component valving in and around the door. It is also to be recognized that the cam 66 could be mounted to extend away from the end of the cylinder 44 and adapted to move with the end of the piston rod 61 to perform the desired control functions which will be set forth in more detail hereinbelow. The cam member 66 has an elevated cam member 67 adjacent the left most end thereof.

The subdistribution line 16 is connected directly to an input port on a cam operated, two position, control valve 68. The three air control valves 41, 43 and 68 constitute a door position sensing device and each of the valves has a cam engaging member 71, 72 and 73, respectively, each of which is adapted to engage the cam member 66. The cam engaging member 73 of the valve 68 is adapted to engage the elevated cam member 67 when the door 63 is in the closed position such as is illustrated in FIG. 1. The remaining cam engaging members 71 and 72 are adapted to engage the cam member 66 when the door is in the closed position as illustrated in FIG. 1.

The subdistribution line 16 is connected through the air control valve 68 when in the position illustrated in FIG. 1 to a conduit 74 to the input 34 of the OR function valve 32 described above and the air pilot valve 52 on the air control valve 51.

The conduit 39, pressurized from the subdistribution line 14 through the air control valve 22 is connected through the cam operated air control valve 41 to a conduit 76 to an input 77 of a two input, single output OR function valve 78. The OR function valve 78 is similar to the OR function valve 32 described hereinabove and has a pair of inputs 77 and 79 such that a pressurization of either one or both of the inputs 77 and 79 will produce an output signal as at 81 to pressurize a conduit 82 connected to the air pilot valve 53 on the air control valve 51.

The conduit 42 is connected through the valve 43, when the valve 43 is shifted to the position illustrated in FIG. 3 which corresponds to the fully opened position of the door, to the conduit 83 which is connected to the input 79 of the OR function valve 78.

A conduit 84 connects the conduit 57 from the air control valve 22 to an input to the air control valve 24. Pressure is thus applied when the air control valve 22 is shifted to the position illustrated in FIG. 2 to the input to the air control valve 24. When the air control valve 24 is shifted to the position illustrated in FIG. 4,

pressure is immediately applied to the input 86 of a timing circuit 87. The timing circuit 87 is a fully pneumatic timer wherein pressure applied to the input terminal 86 will effect a delay in the actuation of an air pilot valve 88 to shift a two position air control valve 89 against the pressure of a return spring 91. When the pressure in the pneumatic timing device 87 is sufficient to activate the air pilot valve 88, the air control valve 89 will shift to the position illustrated in FIG. 5 so that pressure is applied from the subdistribution line 17 through the air control valve 89 to a conduit 92 which is connected to an air pilot valve 93 secured to the end of the air control valve 38 remote from the air pilot valve 37. The conduit 92 is also connected through another conduit 94 to an air pilot valve 96 secured to the end of the air control valve 22 remote from the air pilot valve 21.

OPERATION (FIGS. 1 TO 6) Although the operation of the door control system described above will be apparent to persons skilled in the art, a brief summary thereof will be given for purposes of convenience.

The door 63 is illustrated in the fully closed position in FIG. 1. It is to be noted that the air control valves 22 and 38 are so shifted in position that the conduits 48 and 56 connected to the opposite ends of the cylinder 44 are connected to the conduit 49 and thence through the air control valve 51 to the exhaust port 58 connected direct to the atmosphere. As a result, and when the door 63 is unlocked, the door 63 may be manually moved to the open position due to the fact that the air on both sides of the piston 47 is permitted to remain at a balanced condition through the exhaust port 58 thereby facilitating such movement.

When it is desired to open the door utilizing the door control system 10, an external pressure is applied to a pressure sensitive mat and the pressure signal applied at 27 effects an activation of the pilot valve 28 to shift the air control valve 18 leftwardly against the return spring 29 as illustrated in FIG. 2. Pressurized air is supplied by the subdistribution line 13 through the now shifted air control valve 18 to the conduit 19 to activate the pilot valve 21 on the air control valve 22 to effect a leftward shifting thereof so that pressurized air in the subdistribution line 14 is applied directly to the right end of the cylinder 44 through the conduit 57 (FIG. 2). The air control valve 38 remains unchanged from the FIG. 1 position to the FIG. 2 position and the air is exhausted from the left end of the cylinder through the conduits 48 and 49 and thence out through the air control valve 51 to the exhaust port 58 connected direct to the atmosphere. As a result, initial door opening movement is rapid. Simultaneous with a leftward or opening movement of the door from the FIG. 1 position to the FIG. 2 position, the cam actuated air control valve 68 is shifted downwardly due to a disengagement carn engaging member 73 with the elevated cam member 67. This effects a discontinuation of the supply of pressurized air from the subdistribution line 16 to the OR function valve 32. However, since pressurized air is now supplied through the air control valve 18 to the conduit 26, pressurized air is supplied to the input 33 of the OR function valve 32 to effect a continued activation of the air pilot valve 37 on the air control valve 38. Simultaneously therewith, the pressure in the still pressurized conduit 26 will effect an activation of the air pilot valve 23 to effect a shifting of the air control valve 24 against the return spring 25 so as to block the flow of pressurized air to the input terminal 86 of the pneumatic timer 87.

The circuit remains in the FIG. 2 position until the door is nearly fully opened as shown in FIG. 3 at which time both of the cam engaging members 71 and 72 of the cam actuated air control valves 41 and 43 have become disengaged with the cam member 66. Upon a disengagement of the cam member 66 with the cam element 72 of the cam actuated air control valve 43, pressurized air is supplied from the subdistribution line 15 through the air control valve 38 to the conduit 42 and thence through the cam actuated air control valve 43 to the conduit 83 and thence through the OR function valve 78 to activate the air pilot valve 53 of the air control valve 51 to effect a leftward shifting thereon against the return spring 54. As a result, the left end of the cylinder 44 is now connected through the conduit 48, the air control valve 38 and the conduit 49 to the air restriction valve 59 connected to the outlet port of the air control valve 51. Thus, the initial door opening movement is slowed adjacent the fully opened position so as to minimize a jarring and shocking action when the door reaches the fully opened position. This will also facilitate a quieter door operation.

If, during the period of time that the door is beginning to open, such as is the case with the circuit in the FIG. 2 arrangement and the door is just starting to open, the external pressure applied to the pressure sensitive mat is removed from the input at 27, the return spring 29 on the air control valve 18 will effect an immediate shifting of the valve 18 rightwardly as illustrated in FIG. 4. Similtaneously therewith, the activation of the air pilot valve 23 for the air control valve 24 is discontinued and the return spring 25 therefor will effect a shifting of the air control valve rightwardly as illustrated in FIG. 4. As a result, pressurized air is now applied through the subdistribution line 14 through the air control valve 22, the conduit 84 and air control valve 24 to the input 86 of the timing circuit 87. If the door is not in the fully opened position, the door movement will continue to open as illustrated in the FIG. 2 and FIG. 3 circuits. However, upon the pneumatic timing circuit 87 accumulating pressure to a cartain desired level, the pilot valve 88 for the air control valve 89 will be activated to shift the air control valve 89 leftwardly against the return spring 91 to effect the supply of pressurized air from the subdistribution line 17 through the air control valve 89 to the air pilot valves 93 and 96 of the air control valves 38 and 22, respectively, to shift same simultaneously rightwardly to reverse the supply of air to the ends of the double ended cylinder 44, such as is specifically illustrated in FIG. 5.

Simultaneous with a shifting of air control valve 38, pressure from the subdistribution line 15 through the air control valve 38 to the conduit 42 is immediately discontinued so that the air pilot valve 53 on the air control valve 51 is deactivated and the return spring 54 will shift the valve 51 to the FIG. 5 position to connect the right end 56 of the pneumatic cylinder 44 to the exhaust port 58 which is connected direct to the atmosphere so that the initial door closing movement is a rapid movement.

The circuit of FIG. 5 will remain unchanged during the rapid door closing movement until the cam member 66 engages the cam element 71 of the cam actuated valve 41 as illustrated in FIG. 6 which effects an upward shifting of the air control valve so that pressurized air is supplied from the subdistribution line 14 through the air control valve 22 to the conduit 39 and thence through the air control valve 41 to the input 77 of the OR function valve 78. This will effect an output function at 81 to activate the air pilot valve 53 of the air control valve 51 to a sufficient degree to overcome the pressure of the return spring 54 to shift the valve leftwardly to connect the conduit 49 to the air restriction valve 59 to slow the movement of the door from the initial door closing speed to a slower speed adjacent the fully closed position.

When the door reaches the fully closed position, the elevated cam 67 will engage the cam element 73 to shift the valve 68 upwardly and the circuit will return to the stage illustrated in FIG. 1 and described in detail hereinabove.

If at any time during the door closing movement an external pressure is applied to the pressure sensitive mat, pressurized air will be supplied through the subdistribution line 13 through the shifted (FIG. 2) air control valve 18 to activate the air pilot valve 21 and 37 of the air control valves 22 and 38, respectively, to shift each of the valves leftwardly to apply pressurized air to the right end of the cylinder 44 to effect a door opening movement.

ALTERNATE CONSTRUCTION (FIGS. 7 TO 12) FIGS. 7 to 12 illustrate a modified circuit diagram of a door control system A. The components of the modified door control system 10A will be referred to by the same reference numerals designating corresponding parts of the door control system 10 but with the suffix A added thereto.

For purposes of illustration, FIG. 7 is a schematic diagram of the door control system 10A when the door is in the fully closed position. The solid lines in the circuit are pressurized from a source of pressurized air 11A and the broken lines are not under pressure at the time. This same type of circuit illustration is used in FIGS. 8 to 12 which illustrate the shifted positions of the various air control valves depending upon the direction of movement of the door as well as the position of the door.

Referring now more specifically to the circuit of FIG. 7, the door control system 10A is supplied by pressurized air through a two position, air operated, pilot controlled, spring return valve 101 to a line 102 and to several subdistribution lines 103 and 104. An air operated pilot valve 106 and the two position, air operated, pilot controlled, spring returned valve 101 are initially energized by the pressurized air from the source 11A through lines 107. Energization of the pilot valve 106 shifts the valve 106 into the left hand position as illustrated in FIG. 7 against the urging of the return spring 108.

The subdistribution line 104 is connected through a two position, air operated, spring return pilot controlled valve 111 to a line 1 12 which is connected to an air operated pilot valve 113 on a two position, air operated pilot controlled, spring returned, valve 114 as well as a pneumatic timing device 116 through a conduit 117. A spring 115 serves to return the valve 114 to the position illustrated in FIG. 7 when the pilot valve 113 becomes deactivated. The air operated pilot controlled valve 111 is shiftable leftwardly by a signal produced from a fluidic mat 27A, which signal is pressure signal created by a person stepping on the mat whenever it is desired to open the door, which signal is applied to an air pilot valve 28A of the valve 111. A spring 118 schematically illustrated serves to return the valve 111 to the position illustrated in FIG. 7 when the mat signal applied at 27A is turned off, such as by the removal of the applied external pressure to the mat.

The valve 1 1 1 has two input ports, one input port 1 19 (FIG. 7) being connected to the subdistribution line 104 and the other input 121 being connected to an air restriction valve 122.

The subdistribution line 103 is connected through the valve 114 to a line 123 which in turn is connected to the left end of an elongated, pneumatic cylinder 44A. The valve 114 has three input ports 126, 127 and 128 and two output ports. The input terminal 127 is connected to the subdistribution line 103. The right end of the pneumatic cylinder 44A is connected through a line 129 to one of the two outlet ports 131 of the valve 114. The line 123 is connected to the outlet port 132.

A conduit 133 connects the port 126 on the valve 114 to an input port 134 of a two position, cam operated, spring return valve 136.

As in the embodiment of FIGS. 1 to 6, a piston 47A is provided in the cylinder 44A and is connected through an elongated piston rod 61A which extends through one end thereof to a bracket assembly 62A which is fastened to a movable door assembly (not illustrated in FIGS. 7 to 12). An elongated cam 66A is secured to the bracket assembly 62A and extends generally parallel and coextensively with the elongated cylinder 44A when the door is in the closed position. Again, it is to be recognized that this arrangement is specifically utilized in order to minimize the space of the component valving in and around the door. It is also to be recognized that the cam 66A'could be mounted to extend away from the end of the cylinder 44A and adapted to move with the end of the piston: rod 61A to' perform the desired control functions which will be set forth in more detail hereinbelow.

The valve 136 has a cam engaging member 137 which is adapted to engage the cam member 66A. A,

conduit 138 connects the port 128 to an input port 139 of a two position, cam operated, spring return air control valve 141. The valve 141 has a cam engaging member 142 which is adapted to engage the cam member 66A.

Both of the valves 136 and 141 have a pair of output ports 143, 144 and 146, 147, respectively. An air restriction valve 148 is connected to the outlet port 144 of the valve 136. An air restriction valve 149 is connected to the outlet port 146 of the valve 141. Return springs 151 and 152 serve to resiliently urge the cam engaging member 137 and 142 of the valves 136 and 137, respectively, into engagement with the cam member 66A.

OPERATION (FIGS. 7 TO 12) Although the operation of the door control system 10A described above with respect to FIGS. 7 to 12 will be apparent to persons skilled in the art, a brief summary thereof will be given for purposes of convenience.

The door (not illustrated in FIGS. 7 to 12) is assumed to be in the fully closed position in FIG. 7. Further, the valve 101, while not illustrated in detail in FIGS. 8 to 12, is, nevertheless, assumed to be a part of the embodiment of FIGS. 8 to 12. If, for example, the pressurized air from the source 11A should fail, energization of the valve 101, by reason of a connection of the air pilot valve 106 to the source of pressurized air, becomes deenergized, the return spring 108 will shift the valve 101 to the left thereby connecting the distribution line 102 to the atmosphere so that the piston 47A will be permitted to move freely leftwardly in the cylinder 44A to permit a manual opening of the door.

When it is desired to open the door utilizing the door control system A, an external pressure is applied to a pressure sensitive mat and the pressure signal applied at 27A effects an activation of the pilot valve 28A to shift the air control valve 111 leftwardly against the return spring 118 as illustrated in FIG. 8. Pressurized air is supplied by the sudistribution line 104 through the now shifted air control valve 111 to the conduit 112 to activate the pilot valve 113 on the air control valve 1 14 to effect a leftward shifting thereof so that pressurized air in the subdistribution line 103 is applied to the outlet port 131 and the conduit 129 and thence to the right end of the cylinder 44A. The air to the left of the piston 47A is exhausted from the left end of the cylinder through the conduit 123, outlet port 132 of the valve 114, line 133 and thence out through the outlet port 143 of the valve 136. Since the outlet port 143 is connected directly to the atmosphere, air is permitted to escape freely from the cylinder without restriction. As a result, the initial door opening movement is rapid.

The circuit remains in the FIG. 8 condition until the door is nearly fully opened as shown in FIG. 9 at which time both of the cam engaging members 137 and 142 of the cam actuated air control valves 136 and 141, respectively, have become disengaged from the cam member 66A. Upon a disengagement of the cam member 137 from the cam member 66A, the conduit 123 is connected to the restriction valve 148 to restrict the exit of air from the left end of the cylinder 44A. Thus, the initial door opening movement is now slowed adjacent the fully opened position so as to minimize a jarring and shocking action when the door reaches the fully opened position. This will also facilitate a quieter door operation.

If, during the period of time that the door is beginning to open, such as is the case with the circuit in the FIG. 8 condition and the door is just starting to open, the external pressure applied to the pressure sensitive mat is removed from the input at 27A, the return spring 118 on the air control valve 111 will effect an immediate shifting of the valve 111 rightwardly as illustrated in FIG. 11). However, the air which was permitted to enter into the conduit 112 was sufficient to pressurize the pneumatic timing device so as to facilitate a continued operation of the door opening movement. That is, the door opening movement will continue toward the opened position as illustrated in the FIGS. 8 and 9 circuits. However, upon the pneumatic timing device 116 depleting its pressure to a certain desired level, the pilot valve 113 for the air control valve 114 will become deactivated so that the return spring 115 will shift the air control valve 114 rightwardly to effect the supply of pressurized air from the subdistribution line 103 through the conduit 123 to the left end of the cylinder 44A. This will effect a closing of the door. If, on the other hand, the signal at 27A remains unchanged, the door will remain in the fully opened position illustrated in FIG. 9 until such time that the pressure is removed from the pressure sensitive mat.

Once the penumatic timing device 116 has depleted its stored pneumatic energy as illustrated in FIG. 11, the pilot valve 113 will become deenergized and the return spring will return the valve 114 to the left hand position as illustrated in FIG. 11. Thus, pressure will be supplied from the subdistribution line 103 through the conduit 123 through the left end of the power cylinder 44A. As a result, the initial door closing movement is a rapid movement.

The circuit of FIG. 11 will remain unchanged during the rapid door closing movement until the cam member 66A engages the cam element 142 of the cam actuated valve 141 as illustrated in FIG. 12 which effects an upward shifting of the air control valve so that pressurized air is supplied through the air restriction valve 149. Thus, the air exiting from the door operator system will be restricted and, as a result, the air exiting from the right end of the cylinder through the conduit 129, valve 114, conduit 138 and air restriction valve 149 will check the door closing movement adjacent the fully closed position and effect a door closing speed which is slower than the initial door closing speed.

When the door reaches the fully closed position as illustrated in FIG. 7, the circuit will again assume the FIG. 7 position.

Although particular preferred embodiments of the invention have been disclosed in detail for illustrative purposes, it will be recognized that variations or modifications of the disclosed apparatus, including the rearrangement of parts, lie within the scope of the present invention.

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A pneumatically operated system for controlling a pneumatic cylinder having a double acting piston connected to a door to move said door between open and closed positions, the movement of which is initiated by a pressure sensitive mat which is depressed to open said door, comprising:

a source of pressurized air;

means for sensing the depression of said mat and producing a signal in response thereto;

valve means responsive to said signal to effect a directing of a supply of said pressurized air to one end of said pneumatic cylinder and to effect opening movement of said door;

timing means for generating a change signal at the end of a preselected time period following the discontinuation of the depression of said mat and the effecting a redirecting of said supply of said pressurized air to the other end of said pneumatic cylinder and to effect a closing movement of said door; and

three door position sensing means for detecting the position of said door, a first one of said door position sensing means being adjacent the fully opened position, a second one of said door position sensing means being adjacent the fully closed position, a third one of said door position sensing means being at the fully closed position, said first and second door position sensing means including a single valve having a restricted first outlet connected to the atmosphere and a second unrestricted outlet connected to the atmosphere, said first and second door position sensing means connecting the exiting air from said system to said restricted first outlet when the position of said door is adjacent the fully open and closed positions during a door opening and door closing operation, respectively, and connecting the exiting air from said system to said second unrestricted outlet connected directly to the atmosphere when the position of said door is between said positions adjacent said fully opened and fully closed positions, said third door position sensing means connecting both ends of said pneumatic cylinder to said atmosphere through said second outlet when said door is at said fully closed position. 2. A pneumatically operated door control system according to claim 1, wherein said door includes means defining a cam surface connected thereto and movable therewith; and

wherein said door position sensing means comprises three cam operated air control valves each responsive to a different position of said cam means and thence said door to control the connection of said exiting air to said restricted first outlet and said second unrestricted outlet connected directly to said atmosphere. 3. A pneumatically operated door control system according to claim 1, wherein said timing means is a pneumatically operated timer responsive to the same air pressure that is utilized to open and close the door. 4. A pneumatically operated system for controlling a pneumatic cylinder having a double acting piston connected to a door to move said door between open and closed positions, the movement of which is initiated by a pressure sensitive mat which is depressed to open said door, comprising:

a source of pressurized air; means for sensing the depression of said mat and directing a supply of said pressurized air to one end of said pneumatic cylinder to effect opening movement of said door;

timing means for generating a change signal at the end of a preselected time period following the discontinuation of the depression of said mat;

means responsive to said change signal for redirecting said supply of pressurized air from said one end of said cylinder to the opposite end of said cylinder to effect closing movement of said door;

door position sensing means for detecting the position of said door and (l) producing an opening signal in response to saiddoor opening movement near the fully open position and (2) producing a closing signal in response to 'the door movement near the fully closed position; and

a single air flow control valve having plural outlet ports, one of said ports being connected in circuit with an air restriction valve and another of said ports being connected directly to atmosphere, said air control valve being (1) responsive to said opening signal for connecting said other end of said cylinder to said air restriction valve to effect a slowing of said door opening movement near said fully open position to a speed less than the initial door opening speed and (2) responsive to said closing signal for connecting said one end of said cylinder to said air restriction valve to effect a slowing of said door closing movement near said fully closed position to a speed less than the initial door closing speed. 5. A pneumatically operated door control system according to claim 4, wherein said door position sensing means also senses the position of said door in the fully closed position and produces a third signal; and

including a second air flow control valve responsive to said third signal to effect a connection, when said external pressure on said mat is insufficient to effect a supply of pressurized air to either end of said pneumatic cylinder, of both ends of said pneumatic cylinder to the atmosphere.

6. A pneumatically operated door control system according to claim 5, wherein said door includes means defining a cam surface connected thereto and movable therewith; and

wherein said door position sensing means comprises at least three cam operated air control valves each responsive to a different position of said cam means and thence said door to produce one of said first, second and third signals.

7. A pneumatically operated door control system according to claim 4, wherein said timing means is a pneumatically operated timer responsive to the same air pressure that it utilized to open and close the door.

8. A pneumatically operated system for controlling a pneumatic cylinder having a double acting piston connected to a door to move said door between open and closed positions, said movement being initiated by a pressure sensitive mat which is depressed to open said door, comprising:

a source of pressurized gas;

means for sensing the depression of said mat and producing a signal in response thereto;

a single valve responsive to said signal to direct a supply of said pressurized gas to one end of said pneumatic cylinder whereby to effect opening movement of said door;

timing means for generating a change signal at the end of a preselected time period following the discontinuation of material depression of said mat, said valve being responsive to said change signal to direct said supply of pressurized gas to the other end of said pneumatic cylinder whereby to effect a closing movement of said door;

means defining a cam surface secured to and movable with said door;

door position sensing means including a pair of cam operated gas control valves responsive to a different position of said cam means and issuing a signal dependent upon the position of said door, each of said cam operated gas control valves having a restricted outlet to the atmosphere and an unrestricted outlet to the atmosphere thereon, at least one of said cam operated gas control valves controlling the gas diseharge from said cylinder while said door is moving toward the opened and closed position by directing said gas discharged from said cylinder through said restricted outlets when said door is near its fully open and closed positions during a door opening and door closing operation, respectively, and for directing said gas from said cylinder to the atmosphere through said unrestricted outlets when said door is between said positions nearly fully opened and nearly fully closed. 

1. A pneumatically operated system for controlling a pneumatic cylinder having a double acting piston connected to a door to move said door between open and closed positions, the movement of which is initiated by a pressure sensitive mat which is depressed to open said door, comprising: a source of pressurized air; means for sensing the depression of said mat and producing a signal in response thereto; valve means responsive to said signal to effect a directing of a supply of said pressurized air to one end of said pneumatic cylinder and to effect opening movement of said door; timing means for generating a change signal at the end of a preselected time period following the discontinuation of the depression of said mat and the effecting a redirecting of said supply of said pressurized air to the other end of said pneumatic cylinder and to effect a closing movement of said door; and three door position sensing means for detecting the position of said door, a first one of said door position sensing means being adjacent the fully opened position, a second one of said door position sensing means being adjacent the fully closed position, a third one of said door position sensing means being at the fully closed position, said first and second door position sensing means including a single valve having a restricted first outlet connected to the atmosphere and a second unrestricted outlet connected to the atmosphere, said first and second door position sensing means connecting the exiting air from said system to said restricted first outlet when the position of said door is adjacent the fully open and closed positions during a door opening and door closing operation, respectively, and connecting the exiting air from said system to said second unrestricted outlet connected directly to the atmosphere when the position of said door is between said positions adjacent said fully opened and fully closed positions, said third door position sensing means connecting both ends of said pneumatic cylInder to said atmosphere through said second outlet when said door is at said fully closed position.
 2. A pneumatically operated door control system according to claim 1, wherein said door includes means defining a cam surface connected thereto and movable therewith; and wherein said door position sensing means comprises three cam operated air control valves each responsive to a different position of said cam means and thence said door to control the connection of said exiting air to said restricted first outlet and said second unrestricted outlet connected directly to said atmosphere.
 3. A pneumatically operated door control system according to claim 1, wherein said timing means is a pneumatically operated timer responsive to the same air pressure that is utilized to open and close the door.
 4. A pneumatically operated system for controlling a pneumatic cylinder having a double acting piston connected to a door to move said door between open and closed positions, the movement of which is initiated by a pressure sensitive mat which is depressed to open said door, comprising: a source of pressurized air; means for sensing the depression of said mat and directing a supply of said pressurized air to one end of said pneumatic cylinder to effect opening movement of said door; timing means for generating a change signal at the end of a preselected time period following the discontinuation of the depression of said mat; means responsive to said change signal for redirecting said supply of pressurized air from said one end of said cylinder to the opposite end of said cylinder to effect closing movement of said door; door position sensing means for detecting the position of said door and (1) producing an opening signal in response to said door opening movement near the fully open position and (2) producing a closing signal in response to the door movement near the fully closed position; and a single air flow control valve having plural outlet ports, one of said ports being connected in circuit with an air restriction valve and another of said ports being connected directly to atmosphere, said air control valve being (1) responsive to said opening signal for connecting said other end of said cylinder to said air restriction valve to effect a slowing of said door opening movement near said fully open position to a speed less than the initial door opening speed and (2) responsive to said closing signal for connecting said one end of said cylinder to said air restriction valve to effect a slowing of said door closing movement near said fully closed position to a speed less than the initial door closing speed.
 5. A pneumatically operated door control system according to claim 4, wherein said door position sensing means also senses the position of said door in the fully closed position and produces a third signal; and including a second air flow control valve responsive to said third signal to effect a connection, when said external pressure on said mat is insufficient to effect a supply of pressurized air to either end of said pneumatic cylinder, of both ends of said pneumatic cylinder to the atmosphere.
 6. A pneumatically operated door control system according to claim 5, wherein said door includes means defining a cam surface connected thereto and movable therewith; and wherein said door position sensing means comprises at least three cam operated air control valves each responsive to a different position of said cam means and thence said door to produce one of said first, second and third signals.
 7. A pneumatically operated door control system according to claim 4, wherein said timing means is a pneumatically operated timer responsive to the same air pressure that it utilized to open and close the door.
 8. A pneumatically operated system for controlling a pneumatic cylinder having a double acting piston connected to a door to move said door between open and closed positions, said movement being initiated by a presSure sensitive mat which is depressed to open said door, comprising: a source of pressurized gas; means for sensing the depression of said mat and producing a signal in response thereto; a single valve responsive to said signal to direct a supply of said pressurized gas to one end of said pneumatic cylinder whereby to effect opening movement of said door; timing means for generating a change signal at the end of a preselected time period following the discontinuation of material depression of said mat, said valve being responsive to said change signal to direct said supply of pressurized gas to the other end of said pneumatic cylinder whereby to effect a closing movement of said door; means defining a cam surface secured to and movable with said door; door position sensing means including a pair of cam operated gas control valves responsive to a different position of said cam means and issuing a signal dependent upon the position of said door, each of said cam operated gas control valves having a restricted outlet to the atmosphere and an unrestricted outlet to the atmosphere thereon, at least one of said cam operated gas control valves controlling the gas discharge from said cylinder while said door is moving toward the opened and closed position by directing said gas discharged from said cylinder through said restricted outlets when said door is near its fully open and closed positions during a door opening and door closing operation, respectively, and for directing said gas from said cylinder to the atmosphere through said unrestricted outlets when said door is between said positions nearly fully opened and nearly fully closed. 